1. Field
One embodiment of the present invention relates to a Session Initiation Protocol (SIP) trunk gateway apparatus. More specifically, the present invention relates to an interface configured to establish connection with both an SIP terminal and an SIP network, an exchange apparatus with the interface apparatus and a control method for use in the interface apparatus.
2. Description of the Related Art
In recent years, an internet Protocol (IP) telephone system which interactively transmits and receives in real time images and voice as packet data via an IP network has become widely used. The IP telephone system may perform extension communication and outside-line origination and termination among main apparatuses as well as may perform inter-extension communication and outside-line origination and termination for each main apparatus to be connected to the IP network. The IP telephone system has widely used SIP as its protocol.
This kind of system registers an SIPURI (terminal ID) of an SIP terminal for each main apparatus in a registration server of an enterprise on an SIP network in advance. In making a telephone call, the registration server authenticates the SIP terminal based on the registered SIPURI (e.g., Jpn. Pat. Appln. KOKAI Publication No. 2006-42176).
Meanwhile, the main apparatus separates IP ports to receive SIP messages at the SIP terminals and the SIP network. In this case, since the SIP terminal (hereinafter referred to as an SIP server function) uses a port number 5060, the IP network (hereinafter referred to as an SIP client function) uses a port number 5062 and they may not use a well-known default port number 5060, setting the SIP terminals and network devices such as a fire wall and an application layer gateway becomes complicated and inconvenient.